INOR'JAMC POISONS 247 



the aliuR'Htaiy tract, intestinal walls, blood, or internal organs; also 

 by forming sulphides with the HgS of the intestinal contents. Accord- 

 ing to Cloetta ^^ immunization against arsenic depends entirely upon 

 a reduction of absorption in the intestine, for the longer arsenic is 

 taken, the less appears in the urine and the more appears in the 

 feces.^" At the same time the resistance to arsenic injected sub- 

 cutaneously is not increased at all, and no increase in resistance can 

 be obtained by repeated subcutaneous injections of sublethal doses. 

 There is, however, reason to question the authenticity of the reputed 

 tolerance of habitues to arsenic (Joachimoglu).^"^ Antimony does not 

 produce tolerance in experimental animals (Cloetta). ^^ The manner 

 in which various inorganic ions antagonize the physiological action of 

 one another (e. g., sodium and potassium, calcium and magnesium) is 

 still an important problem. ^'^ 



Free acids and alkalies are partly neutralized by the alkaline and 

 acid contents of the gastro-intestinal tract, partly by forming com- 

 pounds with the proteins, and partly by the alkalies and carbonic acid 

 of the blood stream. (See "Acid Intoxication," Chap, xviii.) Phos- 

 phorus ^* and sulphides are oxidized after absorption into phosphoric 

 and sulphuric acid, which are in turn neutralized by the alkalinity 

 of the blood and tissues. Lillie ^^ has called attention to the close, 

 palisade arrangement of the nuclei of th^ epithelium lining the ali- 

 mentary tract, which makes it necessary '^f&r all substances absorbed 

 to pass through the zone of their active oxidative influence, a fact 

 undoubtedly of great importance in the defense of the body. 



Reduction of iodic acid, chloric acid, hypochlorous acid, and their 

 salts occurs in the bodv, resulting in their conversion into the much 

 less toxic iodides and chlorides. TeUurhim compounds are also re- 

 duced and rendered insoluble. This reaction occurs to some extent 

 in the intestines ; how much in other organs is unknown. 



Methylation, the addition'' of CH^ groups, is observed in poisoning 

 by tellurium, which is> eliminated in 'the breath as methyl telluride, 

 and also in the sweat and fecesjT^ Selenium, pyridine, and some other 

 substances also combine with methane. The source of the methane is 

 possibly in the xanthine molecule. 



Summary. — There are, therefore, three chief reactions used against 



15 Arch. exp. Path. u. Pharm.,'1906 (54), 196: Corresponbl. Schweizer Aerzte, 

 1911 (41), 737. 



16 Not accepted by Hausmann. Ergebnisse Phvsiol., 1907 (6), .58: or Joachi- 

 moglu, Arch. exp. Path., 1916 (79), 419. 



IT Arch. exp. Path. u. Pharm., 1911 (64), 352. 



17a See Osterhout, Proc. Phil. See, 1916 (55), 533. 



18 Increased tolerance to phosphorus may be obtained by repeated small doses, 

 but it lasts only while the poison is beinor given continuously (Oppol, Ziegler's 

 Beitr., 1910 (49), 543). Accompanying the tolerance are structural changes in 

 the liver cells to which are ascribed some significance bv Oppel. 



loAmer. Jour. Physiol., 1902 (7), 412. 



20 See Mead and Gies, Amer. Jour. Physiol., 1901 (5), 105. Caffein niav be 

 demethylated in the liver, Kotake, Zeit., 'physiol. Chem., 1908 (57), 378. 



